PyMei is a Python media center application. It's
designed to run as a full screen application on an
HTPC, navigated by a keyboard or an LIRC input
device. It plays videos or shows other types of
media using external programs like mplayer. With
its plugin support and themeability, it's aiming
to be a very extensible and customizable media
interface.

Moonlight is an open source implementation of
Silverlight (http://silverlight.net), primarily
for Linux and other Unix/X11 based operating
systems. It lets you develop and run Silverlight
applications on Linux; the engine can also be used
for desktop applications.

Pinnacle PCTV Deluxe/Bungee Console is a small GUI
for PCTV Deluxe/Bungee Tools by Rainer Keuchel.
There are 2 versions of the interface; one written
in Tcl/Tk, and the other written in C, using the
GTK2 libraries.

Smitten differs from traditional media centres in
three major ways. It contains no media playback at
all, which makes it very small (and suitable for
porting to embedded systems) and quick to
initialize. It targets a TV display and interface,
which means there's less information on any
particular screen, and a much simpler control
interface consisting of left, right, up, down, and
select. No mouse is required. It is also highly
skinnable, and cross-platform to most systems.
Essentially, it provides an easy-to-use menu
system that allows the user to navigate a
hierarchy of files, and view them using an
(external) tool.

mplayerd is a simple C daemon designed to control
movie play back via TCP/IP. This daemon is
designed to be the backend; it has no playlist
management, etc. It uses Mplayer to do the actual
movie playing.

MplayerBuddy is a media bookmarking application
designed to keep track of the user's place when
watching videos. It uses mplayer as its back-end
media player. It is excellent for people with very
short attention spans who constantly start and
stop several videos.

GEM stands for Graphics Environment for Multimedia and is an external (plugin) for the computer music software Pure Data. It adds the ability to do real-time graphics (based on OpenGL) and video processing to Pure Data.